Technical Field
The instant disclosure relates to an earphone, and more particular to a dual-frequency earphone.
Related Art
As shown in FIG. 1, a conventional earphone casing A10 has a signal cable A1, a vibrating diaphragm A2, a permanent magnet A3, a voice coil A4, a magnet conductive member A5 and a yoke A6 assembled therein. The voice coil A4 is assembled on the vibrating diaphragm A2 and encloses a periphery of the permanent magnet A3. A gap is defined between the voice coil A4 and the magnet conductive member A5. The permanent magnet A3 is sandwiched between the magnet conducting member A5 and the yoke A6.
The signal cable A1 is connected electrically to the voice coil A4. When acoustic signals are inputted to the voice coil A4 via the signal cable A1, firstly the voice coil A4 generates a magnet field because of the electromagnetic effect. And then, the magnet field is interacted with the magnet conductive member A5 via magnetic forces so as to drive the vibrating diaphragm A2 to vibrate, so that the acoustic signals are converted to acoustic waves for output.
As in the conventional earphone A, generally the acoustic signals includes high frequency acoustic signals and low frequency acoustic signals, so both the high frequency acoustic waves and the low frequency acoustic waves will be generated when the vibrating diaphragm A2 vibrates. However, since the high frequency acoustic waves and the low frequency acoustic waves have different wavelengths and amplitudes, the characters of the two different acoustic waves cannot be distinguished by only one vibrating diaphragm A2, so that in a conventional earphone A, the high frequency acoustic waves and the low frequency acoustic waves have intermodulation distortion drawbacks thereby the voices cannot be performed in a clear manner. Furthermore, since the conventional earphone A is devoid of a structure for adjusting the frequency bands of the high and low frequency acoustic waves, the frequency band of the low frequency acoustic waves of the conventional earphone A cannot be adjusted according to user requirements, and the conventional earphone A can hardly output clear and high-quality high frequency voices.